This invention relates to lamps and more particularly to adjustable medical examining lamps.
When used in medical examinations, it is desirable that lamps be adjustable with respect to height and angle of orientation and that it be possible to make such adjustments with one hand. Toward this end, one type of prior art medical examining lamp includes a pair of tubular standards having telescopingly engaging ends which permits vertical and rotary adjustment. A spring assembly is provided to retain the lamp in its adjusted positions and includes a pair of V-shaped wire spring members fixed by an adapter within the end of one of the standards. Each spring member diverged outwardly from the adapter for engaging the inner surface of the other standard. While such prior art spring assemblies are effective to hold the lamp in its adjusted position, it is not wholly satisfactory because the ends of the springs tend to catch on the welding seams of the outer standard as the lamp is rotated. This results in uneven movement and caused an annoying clicking sound as the spring ends catch on and then snap past the seam.
A second type of prior art spring assembly for medical examining lamps employs a generally U-shaped spring mounted on the end of a cylindrical plug by means of a tubular spacer, an axial coil spring and a bolt, nuts and washers. The plug is rotatably received within the inner standard and the legs of the spring are received within the outer standard for resiliently engaging its inner surface. During operation, the springs slide longitudinally within the outer standard but remain fixed relative thereto upon rotation as the plug rotates within the inner standard. While this prior art lamp assembly eliminates the clicking problem, the spring assembly requires several costly parts such as the plug, the tubular spacer and the coil spring in addition to a bolt, washers and nuts. Furthermore, the U-shaped spring of such prior art assemblies is formed by a bending operation so that the spring force tends to be non-uniform as between different springs.